High pressure γ-to-β phase transition in bulk and nanocrystalline In₂Se₃

ABSTRACT

Pressure-dependent phase transitions of In₂Se₃ bulk powders and nanowire samples were studied at room temperature using synchrotron X-ray diffraction and a diamond anvil cell. γ-In₂Se₃, metastable under ambient conditions, transforms into to the stable high pressure β phase between 2.8 and 3.2 GPa in bulk powder samples and at slightly higher pressures, between 3.2 and 3.7 GPa, in nanowire samples. While the γ phase bulk modulus is similar to that of the β phase, the decrease due to pressure in the unit cell parameter ratio, c/a, is less than half the decrease seen in the β phase. First-principles calculations show that γ-In₂Se₃ has a higher energy and unit-cell volume than β-In₂Se₃, consistent with the experimental observations.

KEYWORDS:

• Indium selenide
• phase transitions
• diamond anvil cell

Acknowledgements

The authors thank the beamline 12.2.2 team at ALS/LBNL and Zhongwu Wang at CHESS for their assistance with the XRD experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by NSF [grant number DMR-1206960]. The Advanced Light Source was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Cornell High Energy Synchrotron Source was supported by the National Science Foundation and the National Institute of Health/National Institute of General Medical Sciences under NSF award DMR-0225180.